As conventional nonferrous-metal furnaces using a melting crucible furnace, batch-type furnaces that have one melting crucible positioned in a cylindrical furnace, which is heated with a heating burner, have mainly been used. The applicant of the present invention proposes a “continuous type” melting and holding furnace (refer to Patent Document 1, for example).
As shown in FIG. 8, the continuous type melting and holding furnace disclosed in Patent Document 1 has a preheating tower 100 for preheating a material (a) to be melted, a melting crucible furnace 101 arranged immediately under the preheating tower 100, and a holding crucible furnace 102 disposed beside the melting crucible furnace 101. The preheating tower 100 can travel on rails 109 mounted on the melting crucible furnace 101. The melting crucible furnace 101 has a melting crucible 104 and a heating burner 105, and the holding crucible furnace 102 has a holding crucible 107 and a holding burner 105A.
Usually, when the continuous type melting and holding furnace 120 is operated, combustion gas is supplied from the heating burner 105 into a melting crucible chamber 103 to heat the melting crucible 104, and is introduced into the preheating tower 100 to preheat the material (a) in the form of a solid, and then is discharged from an exhaust port 100A. Molten metal (b) that results from heating the material (a) in the melting crucible 104 is supplied to the holding crucible 107 of the holding crucible furnace 102.
On the other hand, the combustion gas supplied from the holding burner 105A to the holding crucible chamber 106 heats the holding crucible 107 to maintain the temperature of the molten metal (b), and then is introduced into the melting crucible chamber 103 to join with the combustion gas from the heating burner 105. In such a way, the mixed combustion gas is used as the preheating source of the material (a).
[Patent Document 1] Japanese Unexamined Patent Publication No. 2000-130948